A simple and hassle-free form tool for integrating with the website Wordpress

I need to integrate a simple online form tool into several of my websites, but I've tried many platforms and none of them work. I've even paid for platforms that stopped working after a few months, which is very frustrating. I work in the home furnishing industry, specializing in custom-made doors and windows. I'm located in Foshan, Guangdong, China. To facilitate my foreign trade business, I've used WordPress to create dozens of websites for marketing purposes.